Abstract:
In a first aspect there is provided an extraction lens for a TOF mass spectrometer ion source, said lens including an element having an aperture, said aperture extending through the element so as to form a through channel, such that, in use, ions may pass from one side of the element to the opposite side of the element by passing through said through channel; characterised in that said through channel has a length equal to or greater than 8/10 of the diameter of said aperture. This provides an extraction lens which leads to improved extraction and spatial focussing of ions. In addition, as the length of the through channel formed by the aperture is at least equal to 8/10 of its diameter, field penetration through the extraction lens aperture into the region in front of the sample plate is kept at a low level and ions are not prematurely extracted. The aperture can thus be made larger than would otherwise be possible. A larger aperture is advantageous because compared to a smaller aperture, it does not become quickly contaminated with material sputtered from the sample. It is also easier to direct a laser or other light source through a larger aperture. This is useful when it is desired to direct a light beam onto the sample plate, along a path at a small angle to or substantially coincident with the spectrometer's ion-optical axis.
Abstract:
A time-of-flight mass spectrometer for measuring the mass-to-charge ratio of a sample molecule is described. The spectrometer provides independent control of the electric field experienced by the sample before and during ion extraction. Methods of mass spectrometry utilizing the principles of this invention reduce matrix background, induce fast fragmentation, and control the transfer of energy prior to ion extraction.
Abstract:
Eine hohe Teilchendichte im Abzugsvolumen einer Gasphasen-Ionenquelle und gleichzeitig eine sehr geringe Teilchendichte in der Flugstrecke des Flugzeit-Massenspektrometers bewirkt eine hohe Empfindlichkeit bei gleichzeitig hohem dynamischen Bereich der Intensitätsanzeige. Um dies zu erreichen, ist es notwendig, das Flugzeit-Massenspektrometer in zwei oder mehr Bereiche unterschiedlichen Druckes zu teilen, wobei die verschiedenen Bereiche durch eine Gas-Strömungsimpedanz getrennt sind. Eine maximale Teilchendichte im Abzugsvolumen bei gleichzeitig minimaler Teilchendichte in der Flugstrecke läßt sich erzielen, indem man die Gas-Strömungsimpedanzen(3,6) direkt in die Elektroden(1,2) der Ionenquelle integriert.
Abstract:
An ion accelerator for a time-of-flight mass spectrometer includes a pulsed ion accelerator positioned proximate to a sample plate and having an electrode that is electrically connected to the sample plate. An accelerator power supply generates an accelerating potential on the ion accelerator electrode that accelerates a pulse of ions generated from the sample positioned on the sample plate. An ion focusing electrode is positioned after the pulsed ion accelerator. A potential applied to the ion focusing electrode focuses the pulse of ions into a substantially parallel beam propagating in an ion flight path. A static ion accelerator is positioned proximate to the ion focusing electrode with an input that receives the pulse of ions focused by the ion focusing electrode. The static ion accelerator accelerating the focused pulse of ions.
Abstract:
A tandem TOF mass spectrometer includes a first TOF mass analyzer that generates an ion beam comprising a plurality of ions and that selects a group of precursor ions from the plurality of ions. A pulsed ion accelerator accelerates and refocuses the selected group of precursor ions. An ion fragmentation chamber is positioned to receive the selected group of precursor ions that is refocused by the pulsed ion accelerator. At least some of the selected group of precursor ions is fragmented in the ion fragmentation chamber. A second TOF mass analyzer receives the selected group of precursor ions and ion fragments thereof from the ion fragmentation chamber and separates the ion fragments and then detects a fragment ion mass spectrum.
Abstract:
An improved trap-TOF mass spectrometer has a set of electrodes arranged to produce both a quadrupolar RF confining field and a substantially homogeneous dipole field. In operation, ions are first confined by the RF field and then, at a selected time, the RF confining field is discontinued and the dipole field is used to accelerate the ions so as to initiate a TOF MS analysis. The apparatus of the present invention may be used alone or in conjunction with other analyzers to produce mass spectra from analyte ions.
Abstract:
A time-of-flight mass spectrometer includes an ion source that generates ions. A two-field ion accelerator accelerates the ions through an ion flight path. A pulsed ion accelerator focuses ions to a first focal plane where the ion flight time is substantially independent to first order of an initial velocity of the ions prior to acceleration. An ion reflector focuses ions to a second focal plane where the ion flight time is substantially independent to first order of an initial velocity of the ions prior to acceleration. An ion detector positioned at the second focal plane detects the ions. The two-field ion accelerator and the ion reflector cause the ion flight time to the ion detector for the ion of predetermined mass-to-charge ratio to be substantially independent to first order of both the initial position and the initial velocity of the ions prior to acceleration.
Abstract:
デュアルステージ式リフレクトロンでの実施例を説明する。(1)ベース電位X A (U)が一様電場からなるリフレクタを想定し、その設計パラメータの調整で全飛行時間T(E)のE=E 0 における1次微分と2次微分を打ち消し、電位値がE 0 となる中心軸上の2次収束位置を求める(マミリン解)。(2)2次収束位置よりも奥側で反射されるイオンのT(E)が一定になるよう、2次収束位置を始点とし、X A (U)に重畳させる補正電位X C (U)を算出する。(3)リアル電位X R (U)=X A (U)+X C (U)が中心軸上に形成されるよう、リフレクタ電極の電圧値を決める。以上のように、マミリン解のベース電位ではエネルギ補償は2次までだが、さらに補正電位の重畳でエネルギ補償を無限の高次まで拡張し、補正電位部で反射されるイオンに対し完全等時性を達成する。また、補正電位開始点の前後でリアル電位は滑らかに接続され、一様電場からのズレが最小であるため、イオン軌道の発散及び軸外れによる時間収差は最大限に抑制される。
Abstract:
A charged particle spectrum analysis apparatus comprising an electric field generator (11) arranged to subject charged particles to a time- varying electric field, a detector to record charged particle time spectrum data of charged particles which have passed through the electric field, the detector comprising a position-sensitive detection portion (15), and the time-varying electric field arranged to be activated in synchrony with activation of detector, and the time-varying electric field arranged to subject a predetermined region of said detection portion to consecutive charged particle deflection cycles.
Abstract:
Spectromètre de masse à temps de vol, à rayon pulsé, amélioré permettant d'égaliser les vitesses d'une pluralité d'ions d'iso-masse (compactage des vitesses) en soumettant un groupe d'ions de transition, partiellement séparés en paquets d'ions d'iso-masse, au champ de la force d'accélération dépendant du temps et variant de manière monotone dans le temps. A cet égard, le compactage dans l'espace ou la focalisation dans l'espace s'effectue par une accélération des ions attardés (par rapport aux ions en avance) dans un paquet donné d'ions d'iso-masse. La forme d'onde du champ d'accélération des ions peut ressembler à une forme de limitation exponentielle dans le temps et dépend des divers paramètres physiques et de tension associés à la source d'ions, aux grilles d'accélération et aux distances de dérive des ions. Lorsque le profil du champ de la force d'accélération est déterminé correctement à la fois dans l'espace et dans le temps, le compactage des vitesses et le compactage de l'espace sont effectués simultanément pour une grande gamme de paquets d'ions d'iso-masse et la résolution de masse pour des ions de masse plus lourds est particulièrement améliorée. La sensibilité inhérente de cet instrument pour la détection d'ions de masse lourds est conservée et l'espacement des intervalles des temps d'arrivée est plus uniforme qu'avec les spectromètres de masse à temps de vol actuels qui utilisent des champs d'accélération à tension constante.